KR102182810B1 - Method for Hybrid Transceiver Simultaneous Design in OFDM-based Wideband Multi-antenna System - Google Patents

Abstract

The present invention proposes a hybrid transceiver simultaneous design method in an orthogonal frequency division modulation (OFDM)-based wideband multi-antenna system. According to an embodiment of the present invention, a hybrid transceiver simultaneous design method in an OFDM-based wideband multi-antenna system comprises the steps of: designing a transmission and reception analog beamforming commonly used for each subcarrier by using product information of multiple pieces of subcarrier channel information; and designing a baseband beamforming for an effective channel for each subcarrier.

Description

Simultaneous Design Method for Hybrid Transceiver in OFDM-based Wideband Multi-antenna System {Method for Hybrid Transceiver Simultaneous Design in OFDM-based Wideband Multi-antenna System}

The following embodiments relate to a method of simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system.

Beamforming (beamforming or precoding) technology is a technology in which a transmission signal is concentrated in a specific direction using a plurality of antennas. In particular, it is easy to secure a wide bandwidth in ultra-high frequency channels such as Sub-THz in the 0.1~1 THz band considered in a beyond 5G mobile communication system, and hundreds of thousands of antennas can be used due to the very short wavelength. Therefore, high path attenuation can be overcome by forming a narrow beam width.

In order to apply the existing digital multiple input multiple output (MIMO) technology using multiple antennas, a radio frequency chain as many as the number of antennas is required. However, if a large number of antennas are used, the hardware complexity and power Consumption increases significantly and system implementation becomes impossible. To solve this problem, a digital-analog hybrid beamforming structure that uses a much smaller number of RF chains than antennas is used. Here, the analog beamforming block is a structure composed only of an RF phase shifter capable of controlling only the phase of a signal in order to reduce circuit complexity.

In a broadband multi-antenna system using hundreds of thousands of antennas, spatial sparsity occurs due to physical characteristics such as path attenuation in the microwave channel between the transceivers. When there is a spatial sparse phenomenon, the beamforming gain between the transceivers can be obtained by forming analog beamforming in the physical channel formation direction.

When using an Orthogonal Frequency Division Modulation (OFDM) system to remove intersymbol interference (ISI) of a broadband channel, one well-designed analog beamforming block in the beam direction and FFT (Fast Hybrid beamforming can be designed with baseband beamforming as many as the number of subcarrier channels for all subcarrier channels taken by Fourier Transform)/IFFT (Inverse Fast Fourier Transform). In order to maximize the frequency efficiency of hybrid beamforming, analog beams of a transmitter and a receiver must be matched using all channel information of each subcarrier, and for this purpose, analog beamforming of the transmitting and receiving ends must be formed at the same time.

The method of designing analog beamforming that is limited to a limited beam region and causes an error from the actual channel beam direction or using the average value of subcarrier channel information is not optimal from the viewpoint of the transmission rate considering all subcarrier channels. The transmission rate of the OFDM-based hybrid beamforming system can be improved only when information of all subcarrier channels is reflected.

US Patent Publication No. US20160142922 relates to such a Transceiver Architecture for Multiple Antenna Systems (transceiver design for a multiple antenna system), and describes a technology for separately designing a transmission/reception beamformer using feedback information in an OFDM channel environment.

US Patent Publication No. US20160142922

The embodiments describe a method for simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system, and more specifically, a two-step beamforming system in a broadband hybrid beamforming system using an RF chain less than or equal to the number of antennas. Provide technology.

In the embodiments, in step 1, analog beamforming of the transmitting and receiving end is simultaneously designed using product information of all subcarrier channels, and in step 2, frequency efficiency can be improved by designing baseband beamforming. It is to provide a method for simultaneous design of hybrid transceivers in a broadband multi-antenna system.

A method for simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system according to an embodiment includes: designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And designing baseband beamforming for an effective channel for each subcarrier.

In order to reduce performance degradation in frequency efficiency that occurs when beamforming of a transmitter and a receiver are designed separately, a hybrid transceiver can be designed simultaneously by reflecting information of all the subcarrier channels over two steps.

In the step of designing the analog beamforming, a transmission/reception analog beamformer commonly used by subcarrier channels by searching for beam sets of a transceiver having a product of the subcarrier channel information and a correlation equal to or greater than a preset size in a beam dictionary. ) Can be designed.

In the step of designing the analog beamforming, the beam having a large correlation may be sequentially searched using the beam dictionary to maximize an achievable sum rate of the transmitting/receiving analog beamformer commonly used for each subcarrier.

In the step of designing the analog beamforming, assuming an ideal baseband beamformer, the baseband beamformer is eliminated, and the transmit/receive analog beamformer is approximated by an achievable sum rate formula constituting only the transmit/receive analog beamformer. Can be designed.

The designing of the analog beamforming may include finding a beam set having the largest correlation among transmitted/received analog beams using the beam dictionary; And sequentially searching for a beam set having a large correlation in a beam region orthogonal to the beam set having the largest correlation found using the beam dictionary, wherein the beam set having the large correlation is sequentially found. The transmission/reception analog beamformer can be designed at the same time.

The step of designing the analog beamforming may further include designing an RF beamforming matrix of a transmitter and an RF beamforming matrix of a receiver, respectively, and simultaneously designing the transmission/reception analog beamformer.

In the step of finding the beam set having the largest correlation using the beam dictionary, when the product of the subcarrier channel information and the beam set having the largest correlation are found, each block of the transmitting and receiving analog beamformer may be filled.

In the step of designing the baseband beamforming, the baseband transceiver beamformer may be designed to maximize frequency efficiency by using singular value decomposition of the effective channel information of each subcarrier.

In the designing of the baseband beamforming, the effective channel information corresponding to each subcarrier is decomposed by singular value decomposition, so that the baseband beamformer includes a baseband beamforming matrix corresponding to the kth subcarrier channel of the transmitter and the kth receiver. A baseband beamforming matrix corresponding to a subcarrier channel can be designed.

An OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver according to another embodiment includes: a transmission/reception analog beamformer for designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And a baseband beamformer for designing baseband beamforming for an effective channel for each subcarrier.

In order to reduce performance degradation in frequency efficiency that occurs when beamforming of a transmitter and a receiver are designed separately, a hybrid transceiver can be designed simultaneously by reflecting information of all the subcarrier channels over two steps.

The transmission/reception analog beamformer is a transmission/reception analog beamformer commonly used by subcarrier channels by searching for beam sets of a transceiver having a product of the subcarrier channel information and a correlation equal to or greater than a preset size in a beam dictionary. It can be characterized.

The transmitting/receiving analog beamformer may sequentially find the beam having the large correlation by using the beam dictionary to maximize an achievable sum rate of the transmitting/receiving analog beamformer commonly used for each subcarrier.

The transmission/reception analog beamformer may design the transmission/reception analog beamformer by approximating an achievable sum rate formula constituting only the transmission/reception analog beamformer assuming an ideal baseband beamformer and eliminating the baseband beamformer. have.

The transmission/reception analog beamformer searches for a beam set having the largest correlation among transmission/reception analog beams using the beam dictionary, and the correlation in a beam region orthogonal to the beam set having the largest correlation found using the beam dictionary. By sequentially searching for a larger beam set, the transmission/reception analog beamforming can be designed at the same time.

The transmitting/receiving analog beamformer may finally design the RF beamforming matrix of the transmitter and the RF beamforming matrix of the receiver, respectively, to simultaneously design the transmitting/receiving analog beamforming.

When the transmission/reception analog beamformer finds a beam set having the largest correlation and a product of the subcarrier channel information, each block of the transmission/reception analog beamformer may be filled.

The baseband beamformer may be a baseband transceiver beamformer designed to maximize frequency efficiency by using singular value decomposition of effective channel information of each subcarrier.

The baseband beamformer decomposes the effective channel information corresponding to each of the subcarriers by singular value decomposition, and the baseband beamformer corresponds to the baseband beamforming matrix corresponding to the k-th subcarrier channel of the transmitter and the k-th subcarrier channel of the receiver. The baseband beamforming matrix can be designed.

According to embodiments, it is possible to provide a hybrid transceiver simultaneous design method in an OFDM-based broadband multi-antenna system that can use less or the same number of RF chains than the number of antennas through a two-step beamforming design in a broadband hybrid beamforming system. have.

According to embodiments, in step 1, analog beamforming of the transmitting and receiving end is simultaneously designed using product information of all subcarrier channels, and in step 2, frequency efficiency can be improved by designing baseband beamforming. It is possible to provide a method for simultaneously designing hybrid transceivers in a broadband multi-antenna system based on the above.

1 is a diagram schematically illustrating an OFDM-based broadband multi-antenna system according to an embodiment.
2 is a diagram illustrating a structure of an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver according to an embodiment.
3 is a flowchart illustrating a method of simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system according to an embodiment.
4 is a flowchart illustrating a method of designing analog beamforming according to an embodiment.

Hereinafter, embodiments will be described with reference to the accompanying drawings. However, the described embodiments may be modified in various forms, and the scope of the present invention is not limited by the embodiments described below. In addition, various embodiments are provided to more completely explain the present invention to those of ordinary skill in the art. In the drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

The following embodiments relate to a method of simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system, and a two-step beamforming method in a broadband hybrid beamforming system using a number of RF chains less than or equal to the number of antennas. Suggest. In step 1, analog beamforming of the transmitting and receiving end is simultaneously designed using product information of all subcarrier channels, and in step 2, a method of improving frequency efficiency by designing baseband beamforming is proposed.

Broadband hybrid beamforming consists of one analog beamforming and a baseband beamformer for each subcarrier. In order to design one analog beamforming, in the conventional technology, beamforming is designed based on the feedback information by dividing the beam region, or by using the average value of all subcarrier channel information. This has a problem in that the optimal beamforming cannot be designed because the characteristics of the entire subcarrier channel are not properly reflected.

In this embodiment, in order to reflect information on all subcarrier channels, frequency efficiency may be improved by designing a common analog beamforming by using the product of all subcarrier channels. Here, the beam means an antenna pattern formed according to a weight vector multiplied by an antenna array at the transmitting and receiving end.

First, the notation of the system model used below will be described.

는 송신기의 안테나 수이고,

는 수신기의 안테나 수이며,

는 OFDM의 전체 부반송파의 개수(the number of sub-carrier)를 나타내고,

는 각각 송신기와 수신기의 RF chain의 수이며,

는 송신 스트림(stream)의 수이다. 또한,

는 송신기의 송신 전력이고,

는 송신기에서

번째 부반송파를 통해 전송하는 송신신호벡터이다. 그리고,

는 송신기와 수신기 사이의

시간에서 시간 도메인 복합 채널 행렬(time domain complex channel matrix)이고,

이다.

는 송신기와 수신기 사이의

부반송파에서 주파수 도메인 복합 채널 행렬(frequency domain complex channel matrix)이고,

이다.

는 송신기의 RF 빔포밍 행렬이고,

이다.

는 송신기의

번째 부반송파 채널에 해당하는 기저대역(baseband, BB) 빔포밍 행렬이고,

이다.

는 수신기의 RF 빔포밍 행렬이고,

이다.

는 수신기의

번째 부반송파 채널에 해당하는 기저대역 빔포밍 행렬이고,

이다. 또한,

는 수신기 잡음(noise) 벡터이고,

는 잡음(noise) 전력이며,

는 기대 연산자(Expectation operator)이고,

는

단위 행렬(Identity matrix)이고,

는 켤레 전치(conjugate transpose)이다.

Is the number of antennas of the transmitter,

Is the number of antennas in the receiver,

Denotes the number of sub-carriers of OFDM,

Is the number of RF chains of the transmitter and receiver, respectively,

Is the number of transport streams. In addition,

Is the transmit power of the transmitter,

Is At the transmitter

Transmitted through the second subcarrier It is a transmission signal vector. And,

Is between transmitter and receiver

Is a time domain complex channel matrix in time,

to be.

Is between transmitter and receiver

It is a frequency domain complex channel matrix in the subcarrier,

to be.

Is the RF beamforming matrix of the transmitter,

to be.

Of the transmitter

Is a baseband (BB) beamforming matrix corresponding to the subcarrier channel,

to be.

Is the RF beamforming matrix of the receiver,

to be.

Is the receiver's

Is a baseband beamforming matrix corresponding to the subcarrier channel,

to be. In addition,

Is the receiver noise vector,

Is the noise power,

Is the expectation operator,

Is

Is the identity matrix,

Is the conjugate transpose.

1 is a diagram schematically illustrating an OFDM-based broadband multi-antenna system according to an embodiment.

Referring to FIG. 1, an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver according to an embodiment is shown. The broadband multi-antenna system 120 is configured between a transmitter 110 and a receiver 130. The broadband multi-antenna system 120 may include a beamformer, and in this case, a beamformer performing two-step beamforming may be included. More specifically, in the first step, the broadband multi-antenna system 120 designs analog beamforming of the transmitting and receiving ends at the same time using product information of all subcarrier channels, and in the second step, the baseband beamforming is designed to achieve frequency efficiency. Can improve.

In the embodiments, by simultaneously designing a transceiver having a hybrid structure by reflecting information on all subcarrier channels, performance degradation of frequency efficiency that occurs when beamforming of the transmitter 110 and the receiver 130 is separately designed can be reduced. In addition, by simultaneously designing a transmission/reception analog beamformer, frequency efficiency can be improved by designing an appropriate baseband beamformer for an effective channel per subcarrier.

2 is a diagram illustrating a structure of an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver according to an embodiment.

Referring to FIG. 2, an OFDM-based broadband multi-antenna system 120 for simultaneous design of a hybrid transceiver according to an embodiment is a P2P OFDM multiple input/output system including a two-stage hybrid beamformer. , OFDM may be referred to as a multiple input/output system. The OFDM-based broadband multi-antenna system 120 for simultaneous design of a hybrid transceiver according to an embodiment may include a transmission/reception analog beamformer 121 and a baseband beamformer 122.

The transmission/reception analog beamformer 121 may design a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information. Here, the transmission/reception analog beamformer 121 is a transmission/reception analog beamformer 121 that is commonly used by subcarrier channels by searching for beam sets of a transceiver having a product of subcarrier channel information and a correlation equal to or greater than a preset size in a beam dictionary Can be

The transceiving analog beamformer 121 may sequentially find a beam having a large correlation by using a beam dictionary in order to maximize an achievable sum rate of a transceivable analog beamformer commonly used for each subcarrier. For example, the transmission/reception analog beamformer 121 can design a transmission/reception analog beamformer by approximating it with an achievable sum rate formula constituting only the transmission/reception analog beamformer assuming an ideal baseband beamformer and eliminating the baseband beamformer. have.

The transmission/reception analog beamformer 121 searches for a beam set having the largest correlation among the transmission/reception analog beams using a beam dictionary, and a beam set having a high correlation in a beam region orthogonal to the beam set having the largest correlation found using the beam dictionary. Transmitting and receiving analog beamforming can be designed simultaneously by sequentially searching for. Thereafter, the transmission/reception analog beamformer 121 may finally design the RF beamforming matrix of the transmitter 110 and the RF beamforming matrix of the receiver 130, respectively, to simultaneously design the transmission/reception analog beamforming.

In addition, the baseband beamformer 122 may design baseband beamforming for an effective channel for each subcarrier. Here, the baseband beamformer 122 may be a baseband transceiver beamformer designed to maximize frequency efficiency by using singular value decomposition of effective channel information of each subcarrier.

More specifically, the baseband beamformer 122 decomposes the singular value of effective channel information corresponding to each subcarrier, and the baseband beamformer 122 forms a baseband beamforming corresponding to the k-th subcarrier channel of the transmitter 110 A baseband beamforming matrix corresponding to the matrix and the k-th subcarrier channel of the receiver 130 may be designed.

The operation of the OFDM-based broadband multi-antenna system 120 for simultaneous hybrid transceiver design is as follows.

As a proposed two-stage simultaneous transmission and reception beamforming design method, the product of subcarrier transceiver channel information is used. After designing transmission/reception analog beamforming with beamforming signals having a high correlation with product information, a process of designing baseband beamforming for effective channel information of each subcarrier is followed.

More specifically, in step 1, beam sets having a high correlation with the product of subcarrier transceiver channel information are searched in a beam dictionary to design a transceiver analog beamformer 121 commonly used by subcarrier channels. Here, the beam dictionary is a set of beam pattern candidates that can be configured according to the azimuth up and down angles at the transmitting and receiving end.

와

을 각각 설계한다.When a transceiver beam set with a high correlation is found, each of the transceiver analog beamformers 121 blocks is filled, and the process of finding a beam with a high correlation among the beam regions orthogonal to the previously designed beams is sequentially performed.

Wow

Design each.

을 특이값 분해하여 기저대역 빔포머(122)

와

을 설계한다.And, after transmitting/receiving analog beamforming in step 2, effective channel information corresponding to each subcarrier

Singular value decomposition of the baseband beamformer (122)

Wow

Design.

3 is a flowchart illustrating a method of simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system according to an embodiment. 4 is a flowchart illustrating a method of designing analog beamforming according to an embodiment.

Referring to FIG. 3, a method for simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system according to an embodiment includes the steps of designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information ( S110), and designing baseband beamforming for an effective channel for each subcarrier (S120).

This is, in order to reduce the performance degradation of frequency efficiency that occurs when the beamforming of the transmitter 110 and the receiver 130 is separately designed, the hybrid structure transceiver is simultaneously designed by reflecting information of all subcarrier channels over two steps. can do.

Hereinafter, each step of a method for simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system according to an embodiment will be described in more detail.

The simultaneous designing method of a hybrid transceiver in an OFDM-based broadband multi-antenna system according to an embodiment may be performed by an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver according to an embodiment described in FIGS. 1 and 2. . Here, an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver according to an embodiment may include a transmission/reception analog beamformer and a baseband beamformer.

Referring to FIGS. 3 and 4, in step S110, a transmit/receive analog beamformer may design a transmit/receive analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information.

More specifically, it is possible to design a transmission/reception analog beamformer commonly used by subcarrier channels by finding beam sets of a transceiver having a product of subcarrier channel information and a correlation equal to or greater than a preset size in a beam dictionary. In order to maximize the achievable sum rate of a transmission/reception analog beamformer commonly used for each subcarrier, beams having a large correlation can be sequentially searched using a beam dictionary. For example, assuming an ideal baseband beamformer, the baseband beamformer may be eliminated, and a transmit/receive analog beamformer may be designed by approximation with an achievable sum rate formula constituting only the transmit/receive analog beamformer.

On the other hand, as shown in FIG. 4, in the step of designing analog beamforming (S110), in the step of designing analog beamforming, the step of finding a beam set having the largest correlation among the transmitted and received analog beams using a beam dictionary ( S111), and sequentially finding a beam set having a high correlation in a beam region orthogonal to the beam set having the largest correlation found using the beam dictionary (S112), and sequentially finding a beam set having a large correlation According to this, it is possible to design a transmission/reception analog beamformer at the same time.

In addition, the step of designing analog beamforming (S110) may further include a step (S113) of finally designing an RF beamforming matrix of a transmitter and an RF beamforming matrix of a receiver, respectively, and simultaneously designing a transmission/reception analog beamformer (S113). I can.

Here, when a beam set having the largest correlation and a product of subcarrier channel information is found, each block of a transmission/reception analog beamformer may be filled. In addition, when a beam set having a high correlation is sequentially searched in a beam region orthogonal to a beam set having the largest correlation found using the beam dictionary, blocks of the transmitting/receiving analog beamformer may be filled.

In step S120, the baseband beamformer may design baseband beamforming for an effective channel for each subcarrier.

In particular, a baseband transceiver beamformer can be designed to maximize frequency efficiency by using singular value decomposition of effective channel information of each subcarrier. More specifically, by decomposing the effective channel information corresponding to each subcarrier by singular value decomposition, the baseband beamformer includes a baseband beamforming matrix corresponding to the k-th subcarrier channel of the transmitter and a baseband beam corresponding to the k-th subcarrier channel of the receiver. You can design the forming matrix.

Hereinafter, a method of simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system and an OFDM-based broadband multi-antenna system will be described in more detail.

Below, a channel model of an OFDM-based broadband multi-antenna system (P2P OFDM multiple input/output system) for simultaneous hybrid transceiver design can be described as follows.

[Equation 1]

는 시간 영역에서 샘플링 시간

을 갖는 delay-d MIMO 클러스터 채널을 나타내고,

는OFDM 시스템 기반 주파수 영역에서

번째 부반송파에 대한 채널을 나타낸다.here,

Is the sampling time in the time domain

Denotes a delay- d MIMO cluster channel with

In the frequency domain based on the OFDM system

Represents the channel for the subcarrier.

Each symbol used in the equation can be expressed as follows.

는 채널에 존재하는 클러스터(cluster) 수이고,

는 채널 클러스터에 존재하는 광선(ray) 수이며,

는 경로 이득이고,

는 펄스 성형 함수(pulse-shaping function)이다. 또한,

는 송신 안테나로 나가는 각 경로 성분의 높이(elevation)/방위각(azimuth angle)이고,

는 수신 안테나로 들어오는 각 경로 성분의 높이(elevation)/방위각(azimuth angle)이다. 그리고,

는 송신/수신 배열 안테나의 정규화된 배열 응답 벡터(normalized array response vector)이고,

는 배열 안테나 종류에 따라 정해진다.

Is the number of clusters present in the channel,

Is the number of rays present in the channel cluster,

Is the path gain,

Is the pulse-shaping function. In addition,

Is the elevation/azimuth angle of each path component going out to the transmitting antenna,

Is the elevation/azimuth angle of each path component entering the receiving antenna. And,

Is the normalized array response vector of the transmit/receive array antenna,

Is determined according to the type of array antenna.

번째 부반송파에서의 수신 신호를 다음 식과 같이 나타낼 수 있다. After receiving beamforming,

The received signal on the subcarrier can be expressed as follows.

[Equation 2]

이다.here,

to be.

When the channel information of the subcarrier is known, the hybrid beamforming design that maximizes the overall frequency efficiency can be established by the following channel capacity equation reflecting the RF element constraints.

[Equation 3]

는

인 RF 위상 천이기로 구성된 구현 가능한 빔 벡터 집합이다.At this time,

Is

It is a set of possible beam vectors composed of RF phase shifters.

Hereinafter, a method of simultaneously designing a hybrid transceiver in an OFDM-based broadband multi-antenna system according to an embodiment will be described.

대비 물리적으로 하나인 아날로그 빔포밍 블록으로 구성된다.OFDM-based broadband hybrid beamforming is a communication system in which a phase shifter network is introduced to reduce hardware complexity. In general, the total number of subcarriers is

It consists of one analog beamforming block physically.

The baseband transceiver beamformer is designed to minimize mismatch between beamforming formed by simultaneously designing transmission/reception analog beamforming using all subcarrier channel information, and to maximize frequency efficiency by using singular value decomposition of effective channel information of each subcarrier. can do.

When the channel information of the subcarrier is known, the problem of maximizing the frequency efficiency is set up, and when the constraint that the transceiver constitutes a hybrid beamformer is considered, the following equation can be set.

[Equation 4]

In order to optimally design an analog beamformer commonly applied to a subcarrier channel, a transmission/reception analog beamformer can be designed first, and then a baseband beamformer can be designed.

Specifically, the transmission/reception analog beamformer design is designed by lower bound to eliminate the baseband beamformer using Schur complemen, and then the baseband beamformer can be designed by decomposing singular values for effective channels for each subcarrier. .

In step S110, the transmission/reception analog beamformer may design a transmission/reception analog beamforming commonly used for each subcarrier by using product information of the subcarrier channel information.

In order to maximize the lower bound of a transmission/reception analog beamformer commonly used for each subcarrier, a beam having a large correlation can be sequentially found using a beam dictionary, and can be expressed as the following equation.

[Equation 5]

임을 이용하여 lower bound 수식을

내부의 곱으로 전개하였을 때 아날로그 빔포머에

가 서로 투영(projection)되는 형태로써 다음 식과 같이 근사화 가능하다.When the number of multiple antennas increases

The lower bound formula is

When expanded by internal product, the analog beamformer

Are projected to each other, and can be approximated by the following equation.

[Equation 6]

에 해당하는 송수신 아날로그 빔 중에 상관관계가 큰 빔 세트를 빔 사전을 이용해 찾고, 그에 직교하는 빔 영역에서 상관관계가 큰 빔 세트를 순차적으로 찾아 송수신 아날로그 빔포머를 동시에 설계할 수 있으며, 다음 식과 같이 나타낼 수 있다.

Among the transmission/reception analog beams corresponding to, it is possible to design a transmission/reception analog beamformer at the same time by searching for a beam set with a large correlation among the transmission/reception analog beams corresponding to, using a beam dictionary, and sequentially finding a beam set with a large correlation in the beam region orthogonal thereto. Can be indicated.

[Equation 7]

In step S120, the baseband beamformer may design baseband beamforming for an effective channel for each subcarrier.

As a result of passing through a transmission/reception analog beamformer commonly used for each of the previously designed subcarriers, it is possible to design a baseband transceiver beamformer by decomposing the singular value of effective channel information of each subcarrier.

Table 1 shows the simultaneous design algorithm of an analog beamformer and a baseband beamformer.

을 AoA, AoD angle dictionary를 이용하여 설계한다.

Design using AoA, AoD angle dictionary.

[Table 1]

In the following, each pseudocode block will be described in more detail.

4:

로

에 아날로그 프리코더(analog precoder)를 추가하고자 하며,

in

I want to add an analog precoder to

5:

를 찾기 위해 고려하는 채널 정보로 이루어진 나머지(residual)이고,

이다.

Is the residual (residual) consisting of channel information to be considered to find,

to be.

6:

개의 프리코더(precoder) 후보군과

개의 컴바이너(combiner) 후보군 세트(set)를 구성하여 최종적으로는 이것의 상관관계가 가장 높은

를 찾고자 한다.

Precoder candidates and

A set of combiner candidates is formed, and in the end, it has the highest correlation.

I want to find

8:

로 diagonal의 index l은,

As the diagonal index l is,

를 나타낸다.

Represents.

10:

는 지금까지 구성한

에 직교(orthogonal)한 유효채널(effective channel)(residual)이고,

이다.

Has so far configured

Is an effective channel (residual) orthogonal to,

to be.

As described above, according to the embodiments, the OFDM-based OFDM-based design step over two steps through the common analog beamforming design step for each subcarrier and the baseband beamforming design step for each subcarrier for an effective channel using the product form of subcarrier channel information. Broadband hybrid transceivers can be designed simultaneously.

In the OFDM-based broadband multi-antenna system according to the embodiments, the hybrid transceiver simultaneous design method can be applied to a sub-terahertz beamforming system, which is one of the core technologies of the beyond 5G mobile communication system. In addition, the embodiments can be applied not only to a Beyond 5G mobile communication system, but also to a communication system to which a broadband OFDM hybrid beamforming system is applied.

Meanwhile, in order to secure a frequency band, the use of ultra-high frequency channels such as a sub-terahertz communication system is inevitable, and technology demand for a sub-terahertz communication system is expected to increase. In addition, in future mobile communication systems, as coverage is reduced by using ultra-high frequency channels, high-density small cell networks are constructed, and the demand for technology for low-power, high-efficiency multi-antenna systems is expected to increase.

Embodiments may increase frequency efficiency through accurate hybrid beamforming design that maximizes the performance of all subcarriers using instantaneous channel information. In addition, the embodiments may be applied to a sub-terahertz beamforming system to lead the beyond 5G mobile communication technology market.

The apparatus described above may be implemented as a hardware component, a software component, and/or a combination of a hardware component and a software component. For example, the devices and components described in the embodiments include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA), It can be implemented using one or more general purpose computers or special purpose computers, such as a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications executed on the operating system. In addition, the processing device may access, store, manipulate, process, and generate data in response to the execution of software. For the convenience of understanding, although it is sometimes described that one processing device is used, one of ordinary skill in the art, the processing device is a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of these, configuring the processing unit to behave as desired or processed independently or collectively. You can command the device. Software and/or data may be interpreted by a processing device or to provide instructions or data to a processing device, of any type of machine, component, physical device, virtual equipment, computer storage medium or device. Can be embodyed. The software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable recording media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -A hardware device specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of the program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like.

As described above, although the embodiments have been described by the limited embodiments and drawings, various modifications and variations are possible from the above description by those of ordinary skill in the art. For example, the described techniques are performed in a different order from the described method, and/or components such as a system, structure, device, circuit, etc. described are combined or combined in a form different from the described method, or other components Alternatively, even if substituted or substituted by an equivalent, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and claims and equivalents fall within the scope of the claims to be described later.

Claims (20)

In the simultaneous design method of a hybrid transceiver in an OFDM-based broadband multi-antenna system,
Designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And
Designing baseband beamforming for an effective channel for each subcarrier
Including,
The step of designing the analog beamforming,
The product of the subcarrier channel information and the correlation of the subcarrier channel information are searched in a beam dictionary for beam sets of a transceiver having a predetermined size or more to design a transmission/reception analog beamformer commonly used by subcarrier channels. In order to maximize the achievable sum rate of the transmitting/receiving analog beamformer to be used, the beam having the large correlation is sequentially found using the beam dictionary.
Characterized in, a hybrid transceiver simultaneous design method. The method of claim 1,
In order to reduce the performance degradation of frequency efficiency that occurs when beamforming of the transmitter and the receiver are designed separately, the hybrid structure transceiver is designed simultaneously by reflecting information of all the subcarrier channels over two steps.
Characterized in, a hybrid transceiver simultaneous design method. delete delete In the simultaneous design method of a hybrid transceiver in an OFDM-based broadband multi-antenna system,
Designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And
Designing baseband beamforming for an effective channel for each subcarrier
Including,
The step of designing the analog beamforming,
Design a transmission/reception analog beamformer commonly used by subcarrier channels by searching for beam sets of transceivers whose product and correlation of the subcarrier channel information are greater than or equal to a preset size in a beam dictionary, and is an ideal baseband beamformer. Designing the transmission/reception analog beamformer by approximating with an achievable sum rate formula constituting only the transmission/reception analog beamformer to eliminate the baseband beamformer assuming
Characterized in, a hybrid transceiver simultaneous design method. In the simultaneous design method of a hybrid transceiver in an OFDM-based broadband multi-antenna system,
Designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And
Designing baseband beamforming for an effective channel for each subcarrier
Including,
The step of designing the analog beamforming,
Designing a transmission/reception analog beamformer commonly used by subcarrier channels by searching beam sets of a transceiver having a product of the subcarrier channel information and a correlation equal to or greater than a preset size in a beam dictionary,
Finding a beam set having the largest correlation among transmission/reception analog beams using the beam dictionary; And
The step of sequentially finding the beam set having the high correlation in a beam area orthogonal to the beam set having the largest correlation found using the beam dictionary
Including,
Designing the transmission/reception analog beamformer at the same time by sequentially searching for the beam set having the large correlation
Characterized in, a hybrid transceiver simultaneous design method. The method of claim 6,
The step of designing the analog beamforming,
Finally, designing the RF beamforming matrix of the transmitter and the RF beamforming matrix of the receiver respectively, and simultaneously designing the transmission/reception analog beamformer
The hybrid transceiver simultaneous design method further comprising a. The method of claim 6,
The step of finding the beam set having the largest correlation using the beam dictionary,
When finding a beam set having the largest correlation with the product of the subcarrier channel information, each of the blocks of the transmitting and receiving analog beamformers is filled.
Characterized in, a hybrid transceiver simultaneous design method. The method of claim 1,
Designing the baseband beamforming,
Designing a baseband transceiver beamformer to maximize frequency efficiency by using singular value decomposition of the effective channel information of each subcarrier
Characterized in, a hybrid transceiver simultaneous design method. The method of claim 1,
Designing the baseband beamforming,
By decomposing the effective channel information corresponding to each of the subcarriers by singular value decomposition, the baseband beamformer calculates a baseband beamforming matrix corresponding to the k-th subcarrier channel of the transmitter and a baseband beamforming matrix corresponding to the k-th subcarrier channel of the receiver. To design
Characterized in, a hybrid transceiver simultaneous design method. In an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver,
A transmission/reception analog beamformer for designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And
Baseband beamformer for designing baseband beamforming for effective channels for each of the subcarriers
Including,
The transmitting and receiving analog beamformer,
It is a transmission/reception analog beamformer commonly used by subcarrier channels by searching for beam sets of a transceiver having a product of the subcarrier channel information and a correlation greater than or equal to a preset size in a beam dictionary, and is commonly used for each subcarrier. In order to maximize the achievable sum rate of the transmitting/receiving analog beamformer, the beam having the large correlation is sequentially searched using the beam dictionary
Characterized in, a broadband multi-antenna system. The method of claim 11,
In order to reduce the performance degradation of frequency efficiency that occurs when beamforming of the transmitter and the receiver are designed separately, the hybrid structure transceiver is designed simultaneously by reflecting information of all the subcarrier channels over two steps.
Characterized in, a broadband multi-antenna system. delete delete In an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver,
A transmission/reception analog beamformer for designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And
Baseband beamformer for designing baseband beamforming for effective channels for each of the subcarriers
Including,
The transmitting and receiving analog beamformer,
It is a transmission/reception analog beamformer commonly used by subcarrier channels by searching for beam sets of transceivers whose product and correlation of the subcarrier channel information are greater than or equal to a preset size in a beam dictionary, and an ideal baseband beamformer is assumed. In order to eliminate the baseband beamformer, designing the transmit/receive analog beamformer by approximating with an achievable sum rate formula constituting only the transmit/receive analog beamformer
Characterized in, a broadband multi-antenna system. In an OFDM-based broadband multi-antenna system for simultaneous design of a hybrid transceiver,
A transmission/reception analog beamformer for designing a transmission/reception analog beamforming commonly used for each subcarrier by using product information of subcarrier channel information; And
Baseband beamformer for designing baseband beamforming for effective channels for each of the subcarriers
Including,
The transmitting and receiving analog beamformer,
It is a transmission/reception analog beamformer commonly used by subcarrier channels by searching for beam sets of a transceiver having a product of the subcarrier channel information and a correlation equal to or greater than a preset size in a beam dictionary, and the correlation among the transmission/reception analog beams A beam set having the largest correlation is searched using the beam dictionary, and the beam set having the largest correlation is sequentially found in a beam region orthogonal to the beam set having the largest correlation found using the beam dictionary. Designing foaming at the same time
Characterized in, a broadband multi-antenna system. The method of claim 16,
The transmitting and receiving analog beamformer,
Finally, designing the RF beamforming matrix of the transmitter and the RF beamforming matrix of the receiver respectively, and simultaneously designing the transmitting and receiving analog beamforming.
Characterized in, a broadband multi-antenna system. The method of claim 16,
The transmitting and receiving analog beamformer,
When finding a beam set having the largest correlation with the product of the subcarrier channel information, each of the blocks of the transmitting and receiving analog beamformers is filled.
Characterized in, a broadband multi-antenna system. The method of claim 11,
The baseband beamformer,
A baseband transceiver beamformer designed to maximize frequency efficiency by using singular value decomposition of the effective channel information of each subcarrier
Characterized in, a broadband multi-antenna system. The method of claim 11,
The baseband beamformer,
By decomposing the effective channel information corresponding to each of the subcarriers by singular value decomposition, the baseband beamformer calculates a baseband beamforming matrix corresponding to the k-th subcarrier channel of the transmitter and a baseband beamforming matrix corresponding to the k-th subcarrier channel of the receiver. To design
Characterized in, a broadband multi-antenna system.

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